The present invention is directed to methods for using fiber optic waveguides for temperature monitoring.
The use of fiber optics for transmitting information has recently received a great deal of attention because of the light weight, security, safety, and electrical isolation that can be obtained with a fiber optic system. It has also been proposed to use optical fibers for noninterferometric measurement of temperatures in a paper by Gottlieb et al presented at the Electro-Optics conference in Anaheim, Calif. in October, 1978. Gottlieb et al proposed that the loss of light to the cladding of a waveguide depends upon the temperature of the waveguide. In U.S. Pat. No. 4,151,747 issued to Gottlieb et al, there are described fiber optic temperature monitoring systems.
There are many applications in which it would be advantageous to use a fiber optic system for temperature measurement and monitoring, for which no system has been available. For example, when monitoring the temperature of flammable fluids, it would be preferred to use a non-electrical system to avoid the explosion hazard associated with electrical temperature monitoring systems. In some applications, such as monitoring the temperatures of electrical generators, the high RF noise produced interferes with conventional remote sensing methods. The use of fiber optic systems for monitoring temperatures in these applications andother applications has been hampered by the non-availability of suitable waveguides which have light transmission properties that vary substantially at useful temperatures.
In view of the foregoing, there is a need for systems for monitoring temperatures using fiber optic waveguides.